New York (AP) — The driver of a tour bus that crashed on a New York City highway while returning from a quick overnight trip to a casino, killing 15, has been indicted on manslaughter charges, a law enforcement official said Thursday.

Ophadell Williams has been indicted in Bronx State Supreme Court on several counts, but the official did not know the severity of the charges. The indictment has not been made public and the official spoke to The Associated Press on condition of anonymity.

Williams' attorney did not return a call to The Associated Press. He told the New York Times his client would surrender to authorities. The Bronx district attorney's office, which had been investigating the crash, refused to comment.

The World Wide Travel bus ran off Interstate 95 at daybreak on March 12 as it was returning to Manhattan's Chinatown from an overnight trip to the Mohegan Sun casino in Uncasville, Conn. The crash killed 15 people, mostly Chinese men and women over the age of 40 who were regulars at casinos. A report by the National Transportation Safety Board said the bus veered to the right, crossed the shoulder, hit a barrier and traveled 480 feet as it fell over. Then it slid into a vertical sign support that sheared through the bus at the window line.

Williams has maintained he was alert and awake, and that the crash was touched off when the towering bus was clipped by a tractor-trailer, which forced him to swerve and crash.

Some surviving passengers who are suing Williams have alleged he was asleep. The preliminary NTSB report found that an inspection of a tractor-trailer whose driver came forward as a witness revealed no evidence of contact. The report also found that the bus was traveling 78 mph less than a minute before the crash but then slowed somewhat. The speed limit at the Bronx site is 55 mph.

The report does not cite a cause of the crash, and officials said that would be determined in the final report likely out next year.

Williams' lawyer, Sean Rooney, has disputed the passengers' accounts, saying that Williams was rested and had swerved to avoid the tractor-trailer.

"He doesn't drink, he doesn't even smoke. He takes his job very seriously and he was alert, and is a great driver," Rooney said.

He said police tested the driver's breath and blood for alcohol, and the tests were negative. Police have not confirmed that.

State police said soon after the crash that witnesses reported the driver had been speeding. And state officials say they have evidence of false statements from Williams.

Williams was convicted of crimes using two aliases, state officials say. He served just more than two years for manslaughter for his role in a stabbing in 1990, according to state corrections records. He also served about three years, from 1998 to the middle of 2002, for grand larceny for removing an $83,905 check from a Police Athletic League fund.

He also was arrested by New York City police on June 4, 2003, for driving with a suspended license and for possession of three police radios. In 1987, he was arrested on charges of trying to get on public transportation without paying.

Rooney said Williams had tried to put his criminal past behind him and was dedicated to being a good driver.

"He redeemed himself for his mistakes made years ago," Rooney said. "His life was straight. He was doing well until this horrible accident."

New York state has stepped up inspections of tour buses since the crash. Dozens of buses have been taken out of service after police found problems with logbooks, licenses or equipment.